Early Birds [1955-1957]Have a Super Sharp 1955 to 1957 Thunderbird or just want to learn about them? Show yours off and talk about them here.

brake booster operation

This is a discussion on brake booster operation within the Early Birds [1955-1957] forums, part of the Thunderbird Model Years category; Hi folks. Just rebuilding my '57's brake booster. I understand the general principle of how the vacuum provides power assistance, ...

Hi folks. Just rebuilding my '57's brake booster. I understand the general principle of how the vacuum provides power assistance, reducing the pressure required at the pedal, but I'm not sure of what the control valve(?) does. There's a bypass tube from the back of the main diaphragm chamber to the front. It attaches to the control valve, which has a filter at the front of it. I opened it up - it also has a diaphragm in it, which I've damaged simply by opening it up. What does this secondary diaphragm do? Can I buy a spare anywhere? Thanks in advance.